LOADING EFFECT ON WEAR PRODUCT OF THE DIE DRAWN GUR 1120 ULTRA HIGH MOLECULAR WEIGHT POLYETHYLENE AND NITROGEN BASED-ION IMPLANTATION TO COBALT CHROME ALLOY IN KNEE REPLACEMENT APPLICATION

Abstract

The combination of Ultra High Molecular Weight Polyethylene (UHMWPE) as tibial substitute components paired with cobalt chrome alloy as femoral substitute components are the most common materials widely used in knee replacement applications. Wear mechanism effect on UHMWPE material is one of the leading factors that cause failure of this application.

In this study, the effects of loading in creating wear product and the influence of wear mechanism to alter material wear factor of the UHMWPE was investigated after Pin on Plate Unidirectional Reciprocating Movement Wear Test. This study use a die drawn GUR 1120 UHMWPE pin paired with nitrogen based-ion implantation of cobalt chrome alloy and utilize 25% bovine serum plus 75% distilled water as lubricant.

The materials were paired in a Pin on Plate Wear Test with sliding unidirectional reciprocating movement and subsequently loaded with 353 N and 462 N of force resulted in 9MPa and 12MPa contact pressure with constant friction velocity of 116.5 mm/s.

After the test, there was significant difference of wear product and wear factor subsequent to the loading process with a total of 35 km distance covered and 25 mm average gait length. From the 353 N loaded forces there was 1,075 mm3 of wear product volume created and 4.4 × 10-8 average wear factor observed, while in the 462 N force application there had been no wear product volume and wear factor resulted during the observation. The result of this study demonstrated that greater load produce lesser wear product and wear factor of the die drawn UHMWPE.